I have eagle h-beam 5.7 rods and SRP -31cc pistons I got along w/ a eagle forged crank. However I have noticed some turbo guys running 6.0 rods and different pistons. Should I look into getting something else or am I good with what I have? Motor will be a 383 and will most likely see 20psi.

Thanks
-Mark

 

No problem with the parts, provided this isn't going to be a high rpm motor. However 20psi and pump gas is not goning to be practical, IMHO.

Rich

 

Who says it will be on pump gas I am aware of the octane needed for 20 psi, pump gas will be for low boost street cruising.
So will 7k rpm MAX, most likely lower will be ok with these parts?
-Mark

 

Change the stock Eagle rod bolts to ARP 2000's. Stock Eagle rod bolts are crap.

 

Good advice from Mike on the bolts. But yes, I think you will be fine as far as the basic integrity of the parts you mentioned. I assume the supporting cast of parts will be appropriate and the motor will be correctly assembled. You might consider a partial bloack fill, though many people seem to do fine without it. Along the same lines, 10 over beats 30 over as far as strength goes.

Rich

 

10-4 on the bolts, but please explain the block fill thing? And the block I have is already bored 30 over and stroker clearenced. Plus I dont think the pistons would fit if it was only 10 over would it
-Mark

 

If you were starting from scratch going 10 over (with the appropriate piston) is desirable as it gives thicker, and therefore stronger, cylinder walls. A partial block fill would have a siilar goal of strengthening the block.With 20psi, assuming decent heads, you are going to be making some pretty high cylinder pressures.

Rich

 

Just know, also, that a good machine shop will re-hone after a block-fill because the filler expands when it cures, shrinking the bottom of the bore by as much as .001".

Mike

 

So which are better, 5.7 or 6.0 rods? I thought 5.7s were because it meant more meat on top of the piston. Or, am I way off?

 

Hmmm. . . the age old dilemma. . . the 6" rods are better for power, but 5.7"s allow a stonger piston. Your choice. I had some 5.7 Eagles from a previous engine, so I just used them.

 

I will be using 5.7 eagle h beams, -31cc JE's and cola crank with T76.

 

It does seem as though longer rods have the potential to produce more power, but this would not apply to a forced induction setup. There are many theories as to why longer rods produce (slightly) more hp, but the primary reason is that a longer rod delays peak piston velocity until the piston is further down the bore, which gives the
intake valve more time to open before peak airflow its greatest. By delaying peak piston velocity by a degree or so, the intake valve will be open another 0.010-0.015", With a 350 Chevy, switching to 6" rods from 5.7" ones will delay peak piston velocity
from 74.5° to 75.5°. However, forced induction does not rely on the same "passive" cylinder filling that an NA motor does and this advantage is lost.

No matter what, even under optimal circumstances, the hp difference between a 5.7" and a 6" rod is very, very small. On the order of a couple of hp. The shorter rods advantages for forced induction far outweigh what would amount to less than 1/2%hp increase. The main benefit to the shorter rod is room for the ring pack. The second is that more rapid acceleration of the piston away from TDC may help prevent detonation by lowering peak cylinder pressure.

Rich